TornadoFX key press listener issues - kotlin

Question

When I run the following code
fun main(args: Array<String>) {
Application.launch(HelloWorldApp::class.java, *args)
}
class HelloWorldApp : App(HelloWorld::class)
class HelloWorld : View() {
override val root = hbox {
addEventFilter(KeyEvent.ANY) { event ->
println("pressed:"+event.character)
}
}
}
When I press any keys on my keyboard the println() is never called. Am I missing something?

Answer 1

Simply adding an HBox does not give it focus, and when it doesn't have focus it won't receive key events. You should override onDock and add the listener to the currentScene instead. If you really need to add the listener on the HBox, add the listener and request focus once the view has been docked:
fun main(args: Array<String>) {
launch<HelloWorldApp>(args)
}
class HelloWorldApp : App(HelloWorld::class)
class HelloWorld : View() {
override val root = hbox {
addEventFilter(KeyEvent.ANY) { event ->
println("pressed:" + event.character)
}
}
override fun onDock() {
root.requestFocus()
}
}

Answer 2

Looking for a similar problem I came up with this, which looks simpler, but I do not yet understand any possible subtle differences between using the keyboard control versus explicit focus requesting.
import javafx.scene.input.KeyEvent
import tornadofx.*
fun main(args: Array<String>) {
launch<HelloWorldApp>(args)
}
class HelloWorldApp : App(HelloWorld::class)
class HelloWorld : View() {
override val root = hbox {
keyboard {
addEventHandler(KeyEvent.KEY_PRESSED) { println(it.code) }
}
}
}